I unscrewed my wrench too far and had to send it out for re-calibration. Cost $65 and took 2 weeks. Then I ran across this on Amazon; Alltrade 940759 Powerbuilt Digital Torque Adaptor for 1/2-Inch Driver. Sounds like a pretty good device. Either way, having an accurate device is super important when cranking the bolts almost to the point of snapping.
The name of the outfit is Angle Repair.com. They do good work.